Protein: Nutrient Timing & Distribution -...
-
Upload
dinhkhuong -
Category
Documents
-
view
216 -
download
1
Transcript of Protein: Nutrient Timing & Distribution -...
Protein:Nutrient Timing & Distribution
MATT CARLIN & MELANIE MARSHALL
Introduction:Nutrient Timing
Strategy: maximize exercise-induced muscular adaptations and facilitate
repair of damaged tissue
Pre- vs. post-exercise period
Anabolic window of opportunity?
Window of time existing after training to optimize training-related muscular
adaptations
Effects of Supplement Timing and
Resistance Exercise on Skeletal Muscle
HypertrophyPaul J. Cribb & Alan Hayes
Medicine & Science in Sports & Exercise (2006):38(11);1918-1925
Background
1. Oral supplementation with whole proteins or EAAs immediately before and/or after resistance exercise (RE) shown to promote better anabolic response compared with placebo treatments (Tipton et al. 2003 & 2004)
Presence of CHO enhances response
2. Consumption with PRO-CHO supplement immediately before and after RE MAY provide ideal anabolic conditions for muscle growth
Observed effects: muscle hypertrophy and greater gains in lean body mass (LBM)
3. Supplementation with creatine monohydrate (CrM) shown to promote greater gains in LBM and strength during RE training compared with placebo treated groups
Limitations of Previous Studies
Normal eating patterns inhibited
Lacking control group to assess effects of consuming supplement at other
times during the day
Limited research examining whether taking CrM in hours surrounding RE
may result in greater accumulation of Cr within muscle or provide greater
adaptations compared with supplementation at other times of the day
Purpose
Examine the effects of supplement timing during RE training with a CrM-
containing PRO/CHO supplement in comparison with supplementation at
times not close to the immediate pre- and post-workout periods
Hypothesis:
Supplement timing would provide greater chronic adaptations (greater
increases in LBM, strength, and muscle-fiber hypertrophy) compared with
supplementation in the hours not close to RE
Methods
Single-blind, randomized protocol
Participants: 23 recreational male body-builders
Supplementation: 4x/wk for 10 wks
PRE-POST:
1) Just before commencing workout
2) Straight after finishing workout
MOR-EVE
1) Morning before breakfast
2) Late evening before sleep
Supplement (per 100 g)
40 g PRO (whey isolate)
43 g CHO (glucose)
<0.5 g FAT
7 g CrM
= ~ 267 kcals
Maintained habitual daily diet during trial
3 diet records (before, 1st wk of study, final wk of study)
Wt. measured (before, 1st wk, & final wk of the study)
Methods cont.
Questionnaires used to determine training history (3-5 days/wk for at least 6 mos)
Structured training program 8-12 wkbefore commencing trial
10 wk RE program
Designed to increase strength and muscle size
High-intensity overload workout (compound exercises using free weights)
Training intensity – RM from strength tests
3 phases of progressive overload program
Preparatory (70-75% 1RM)
Overload phase 1 (80-85% 1RM)
Overload phase 2 (90-95% 1RM)
Training diaries
Exercises, sets, reps performed, and wt. used throughout the program
Resistance-Training Protocol
Methods cont.
Following assessment done in the week before and after 10-wk RE program:
Strength – 1RM (barbell bench press, deadlift, squat)
Body composition (DEXA) –
Lean mass
Fat mass
Body fat %
Muscle analysis –
Muscle fiber type (I, IIa, IIx)
Cross-sectional area (CSA)
Contractile protein content
Metabolite concentrations (PCr, Cr, & glycogen)
Results
17 participants completed RE program
Baseline characteristics – Ø differences btwn groups in any variables
Dietary analysis
Ø differences btwn groups
Ø differences btwn groups for fiber proportions
PRE-POST > increases in CSA of type IIa & IIx
fibers and contractile proteins
Results cont.
PRE-POST group ↑ PCr and total Cr concentrations and ↑ muscle glycogen
concentrations after RE program
Discussion
Post 10 wk RE program
Supplementation before and after each workout resulted in significantly > improvements in 1RM
strength and body composition (i.e. ↑ LBM and ↓ body fat %) compared w/ matched group who
had consumed the same supplement at times outside of the pre- and post-workout time frames
Significantly > muscle hypertrophy response from supplement timing at 3 different levels
PRE-POST > increases in:
LBM
Hypertrophy of type IIa & IIx fibers
Contractile proteins
Discussion cont.
Acute-response investigations:
Supplementation w/ protein (or EAA) before and/or after RE enhances anabolic response by:
1) Increasing muscle protein-synthesis rates
2) Decreasing protein degradation
3) Providing a higher net protein balance
Longitudinal studies
Protein supplementation before and/or after RE enhances:
1) Chronic adaptations desired from training (i.e. muscle hypertrophy and strength)
Discussion cont.
1st novel finding
Beneficial effects of supplement timing on strength and muscle hypertrophy were
obtained when participants followed normal eating patterns
Effects likely not attributed simply to the presence or absence of certain
macronutrients in the hours surrounding RE
Adaptations reflect specific interactive effect between high-intensity muscle
contraction and the presence of an abundance of nutritional material
EAA
Cr
CHO
Discussion cont.
Mechanisms
EAA - ↑ acute stimulation of protein synthesis in muscle during RE and to provide > positive net protein balance over a 24-h assessment period
CHO –
Enhance anabolic stimulus by ↑ plasma insulin concentrations (serves to ↑ protein-synthesis rates when EAA are present)
Reducing myofibrillar protein breakdown after RE
Beneficial effects of supplement timing on muscle hypertrophy may be attributed to abundance of EAA and glucose during high-intensity muscle contraction
Discussion cont.
CrM
Supplementation consistently shown to augment LBM and strength
development during RE
CrM + whey PRO = > gain in lean mass vs. whey PRO + CHO
CrM likely contributed to improvements in strength and hypertrophy
observed in both groups
Interesting finding: PRE-POST > muscle Cr concentrations after trial
Discussion cont.
Mechanisms
Enhanced cellular bioenergetics
Greater expression of hypertrophy-related genes
Higher working capacity during RE
Speculation:
Supplement timing promotes more efficient Cr accumulation within muscle
and, therefore, greater strength gains and muscle hypertrophy during RE
training
Discussion cont.
2nd novel finding
PRE-POST group: significantly > muscle glycogen concentrations at the end of the study
High levels attributed to increased availability of CHO and Cr from
supplementation on day of the biopsy?
Levels from weeks 1 and 10 should have been higher for PRE-POST group
Levels from week 1 Ø significantly different from MOR-EVE group
Discussion cont.
PRE-POST supplement timing:
Promoted more efficient CrM accumulation within muscle
Promoted more efficient muscle glycogen restoration
Enabled greater work capacity during workouts = greater strength
improvements and muscly hypertrophy
Limitations
Supplementation PRE & POST workout
Addition of CrM to supplement
Personalized coaching/supervision
Conclusion
PRE-POST supplement timing results in greater strength and body
composition improvements as well as muscle hypertrophy compared with
supplementation at times outside of the workout period
Supplement timing represents a simple but effective strategy to enhance
the adaptations desired from RE training.
Nutrient timing revisited: is there a post-
exercise anabolic window?Alan Albert Aragon & Brad Jon Schoenfeld
Journal of the International Society of Sports Nutrition (2013):10(5);1-11
Goals of Post-Exercise Nutrition
Attenuation of muscle protein breakdown
↑ insulin: anti-catabolic
Potentiates increases in muscle protein synthesis (MPS)
Muscle hypertrophy
Do benefits extend into practice?
Insulinogenic Effect
In presence of elevated plasma amino acids, effect of insulin elevation on net muscle
protein balance plateaus within a range of 15-30 mU/L (~3-4x normal fasting levels)
Accomplished w/ typical mixed meals
~1-2 h for circulating substrate levels to peak
~3-6 h (or more) for a complete return to basal levels depending on the meal size
Recommendation for lifters to spike insulin post-exercise may be trivial
Classical post-exercise objective to quickly reverse catabolic processes to promote recovery
and growth may only be applicable in absence of a properly constructed pre-exercise meal
Muscle Protein Synthesis (MPS)
Stimulatory effects of hyperaminoacidemia on MPS, especially from EAAs,
are potentiated by previous exercise
Maximizing MPS - evidence to support the superiority of post-exercise free
amino acids and/or protein compared to solely CHO or non-caloric
placebo
However evidence lacking for recommendation to consume protein as
soon as possible post-exercise
MPS cont.
Protein synthesis of legs and whole body ↑ threefold when supplement (10 g PRO, 8 g
CHO, 3 g FAT) ingested immediately post-exercise compared to just 12% when
consumption was delayed (Levenhagen et al. 2001)
Ø significant difference in leg net amino acid balance btwn 6 g EAA coingested with 35
g CHO taken 1 h vs. 3 h post-exercise (Rasmussen et al. 2000)
Immediate pre-exercise ingestion of the same EAA-CHO solution resulted in significantly >
and more sustained MPS response compared to the immediate post-exercise ingestion (Tipton et al. 2001 & 2007)
Ø sign. difference in net MPS btwn the ingestion of 20 g whey immediately pre- vs. the same
solution consumed 1 h post-exercise
MPS cont.
Utility of acute studies is limited to providing clues and generating
hypotheses regarding hypertrophic adaptations
Measures of MPS assessed following an acute bout of RE are not necessarily
predictive of long-term hypertrophic responses to regimented RE
CONSENSUS:
Available data lack any consistent indication of an ideal post-exercise
timing scheme for maximizing MPS
Muscle Hypertrophy
Results from studies looking at long-term hypertrophic effects of post-
exercise protein consumption are conflicting due to varied study designs
and methodology
Major limitation: use of both pre- and post-workout supplementation
Difficult to draw relevant conclusions as to the validity of an ‘anabolic
window’
Discussion
Evidenced-based support for an
‘anabolic window of opportunity’ far
from definitive
Hypothesis based on pre-supposition
that training is carried out in a fasted
state
How might pre-exercise nutrition
influence the urgency or effectiveness
of post-exercise nutrition
Primary goal increasing muscle size and/or
strength
Consuming pre-exercise meal 1-2 h prior in
attempt to maximize training performance
Potentially act as pre- and post-exercise meal as
the time course of digestion/absorption can
persist into the recovery period
If training initiated more than ~3-4 h after
preceding meal, classical recommendation of
consuming protein (~20-30g) as soon as
possible MAY be warranted in order to reverse
the catabolic state
Discussion
Generalizability of recommendations
Trained vs. untrained:
Less global response of protein synthesis in advanced trainees
May warrant closer attention to protein timing and type (i.e. high leucine sources)
in order to optimize rate of muscular adaptation
Elderly population:
‘Anabolic resistance’ = lower receptivity to amino acids and resistance training
Likely require higher individual PRO doses to optimize the anabolic response to
training (possibly closer to 40 g)
Discussion
Study Limitations
1. Examining pre- and post-exercise supplementation simultaneously
2. Neglecting to match total protein intake between the conditions
compared
3. Conservative dosing strategies (~10-20 g)
4. Using untrained individuals
5. Differing methods used to assess muscle hypertrophy (accuracy of
measures inexact)
Practical Applications
High-quality protein dosed at 0.4-0.5 g/kg of LBM at both pre- and post-
exercise
Reflects current evidence showing maximal acute anabolic effect of 20-40 g
Pre- and post-exercise meals should not be separated by more than ~3-4 h
(given a typical training bout lasts ~45-90 min)
If protein delivered within a large mixed-meal, possibly lengthen the interval to
5-6 h
Introduction:Nutrient Distribution
Recovery from exercise happens 24/7
Not just post-exercise
How can we maximize recovery in areas outside of the “anabolic
window?”
Protein intake?
Dietary Protein Distribution Positively
Influences 24-h Muscle Protein Synthesis in
Healthy AdultsMadonna M. Mamerow et al.
Journal of Nutrition (2014):1-5
Background
Current RDA sufficient to prevent deficiency
Optimal health?
Prevention of sarcopenia?
Enhancement of LBM and strength?
Adult protein intake 3x greater at dinner than breakfast (NHANES, 2012)
38g V 13g
Background
30g PRO per meal has been shown to increase MPS maximally
Is this the complete picture?
MPB may be more dynamic than originally thought
Populations…
Background
Amino Acids:
Potently stimulate MPS
MPB mostly unchanged (Glynn et al, 2010)
The increase in MPS from exogenous amino acid delivery is transient, peaking at 1-2 hours and returns to baseline afterwards (Bohe et al, 2001)
Increases or decreases in muscle mass occur from changes in net protein balance over time
NPB
Fasted
Fed
Hypothesis
Even spread (30-30-30) more beneficial than typical intake (10-15-65)
Participants and Methods
Participants
8 males and females 25-55 YO
No metabolic disease, obesity, recent weight loss/gain, anabolic steroid usage
Active, but not athletically trained
Design
7-d crossover with 30-d washout
Metabolic studies days 1 and 7
Account for habituation
Methods
Hospital admittance
No exercise within 72h
Standardized meal the evening before
Overnight fast
Metabolic Study
Primed, constant phenylalanine infusion
Biopsies at 900, 1230 and 900 (24h post)
Meals at 930. 1300 and 1700
Venous samples before meals and at 20 min intervals for 2-3 hour postprandial
Methods
Are metabolic study conditions realistic for an athletic population?
7 days of constant PRO intake, then second metabolic study
Prepackaged meals
Measuring MPS
Fractional Synthetic Rate (FSR)- measure incorporation of phenylalanine into
mixed muscle protein
Results
Breakfast Meal (30g V 10g) 24-hour FSR
EVEN 30% higher EVEN 25% higher
Discussion
Daily quantity of protein not the sole determinant of increasing MPS
Recommendation/RDA?
High protein containing evening meal (65g) not sufficient to make up for
earlier deficits in MPS
Muscle protein breakdown?
Inability to measure both MPS and MPB in same study
40-40-40 better than 30-30-30?
Discussion
Higher frequency?
4x/day? 5x/day? 8x/day?
Small contribution to increasing LBM and strength
Final Discussion
Efficacy of post exercise supplementation when other protein is equally distributed?
Class question- optimal protein dosing throughout the day?
Meal-EAA-meal-EAA-meal for lower caloric intake but higher optimal MPS?
Application- how to increase protein frequency?
What foods would be good for on-the-go? Refrigeration consideration?